A typical histone H 1 can be purified from Aspergillus nidulans We have cloned, sequenced and deleted the gene (hhoA) coding for this protein. This gene comprises six introns. The position of one of the introns is identical to that found in a number of H1 plant histories. The peptidic sequence show the three typical domains including a recognisable globular domain. The closest similarity is found with the two globular domains of the H 1-like protein of Saccahromyces cerevisiae. Thus, the gene coding for the latter protein probably originated by internal duplication of the globular domain in a typical H1-coding gene. Deletion of hhoA results in complete disappearance of the H1 protein defined by electrophoretic mobility and PCA solubility. The deleted strain has no apparent phenotype. We have analysed growth, conidiation, conidial viability, UV and DMSO sensitivity, the appearance of resting and mitotic nuclei, the sexual cycle and ascospore viability. The nucleosomal repeat is identical in hhoA+ and hhoA- strains. We have analysed the nucleosomal structure of a number of promoters, including the niiA-niaD and prnD-prnB bidirectional promoters. In both expression is associated with important chromatin rearrangements The former shows complete nucleosome loss under conditions of full expression. This nucleosome loss is independent from transcription and strictly dependent on the activity of the GATA factor AreA. The deletion of hhoA does not change either the structure of the resting promoters nor the alterations associated with expression. The role of linker histories in fungi remains an open question.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)